Flush toilet

ABSTRACT

A flush toilet according to the present invention includes a bowl including a bowl-shaped waste receiving surface, a rim, a spouting port formed in the rim and a pooled water portion having a front region and a rear region, and includes a configuration where a ratio of an inflow flow rate of flush water into the front region of the pooled water portion in a second half of flushing period in a flushing period to “a total inflow flow rate of flush water into the pooled water portion” is larger than a ratio of an inflow flow rate of flush water into the front region of the pooled water portion in a first half of flushing period to “the total inflow flow rate of flush water into the pooled water portion”.

BACKGROUND OF THE INVENTION Field of the Invention

The present invention relates to a flush toilet, particularly to a flush toilet that is flushed with flush water supplied from a flush water supply source to discharge waste.

Description of the Related Art

Conventionally, for example, such a flush toilet as described in Japanese Patent Laid-Open No. 2017-179958 is known, which makes it easy for flush water spouted from a first rim spouting port to reach a fourth divided region located in right front of a bowl.

Further, for example, such a flush toilet as described in Japanese Patent Laid-Open No. 2021-55437 is known in which a first circulating flow having a large circulating radius of flush water spouted from a first spouting port flows into a first region to facilitate discharge of waste and in which second flush water spouted from a second spouting port flows into a second region.

Further, for example, such a flush toilet as described in Japanese Patent Laid-Open No. 2019-190217 is known in which flush water spouted from a first spouting portion of a rim generates a first branch flow in a front portion of a waste receiving surface, and this first branch flow forms a main flow downward from the waste receiving surface toward a pooled water portion. Also, flush water spouted from a second spouting portion flows downward from a right rising wall surface of the pooled water portion into the pooled water portion, to form a vertical circulating flow in the pooled water portion. Then, these two flows join each other to form an induced flow that pushes waste into a toilet discharge passage.

However, in the flush toilets of Japanese Patent Laid-Open No. 2017-179958, Japanese Patent Laid-Open No. 2021-55437, and Japanese Patent Laid-Open No. 2019-190217 described above, as the flush water circulating along a bowl surface in a second half of flushing decreases, a flow that submerges waste into pooled water also weakens. As a result, a problem occurs that floating waste is not easily discharged and the floating waste remains in a well portion.

To solve the problem, the present inventors have made an earnest study and found out that discharge capacity of floating waste can be improved by increasing an inflow flow rate of flush water into a front region of the pooled water portion in the second half of flushing period and that the floating waste can be inhibited from being undischarged and remaining.

However, a new problem occurs that, when flush water spouted from the spouting port forms a circulating flow on a bowl surface and this circulating flow flows into the pooled water portion, a region where the flush water flows into the pooled water portion changes as a flow rate of flush water changes, and the inflow flow rate into the front region of the bowl in the second half of flushing decreases.

Therefore, it is an object of the present invention, which has been made to solve the problems of the prior art and newly occurring problems, to provide a flush toilet that increases a ratio of an inflow flow rate into a front region of a pooled water portion in a second half of flushing period and that can improve a discharge capacity of fine waste particles in the second half of flushing period.

SUMMARY OF THE INVENTION

In order to achieve the above-described object, the present invention provides a flush toilet that is flushed with flush water supplied from a flush water supply source to discharge waste, the flush toilet including a bowl that receives waste and that includes a bowl-shaped waste receiving surface, a rim formed above the waste receiving surface, a spouting port that is formed in the rim and that spouts flush water, and a pooled water portion formed below the waste receiving surface, the pooled water portion having a front region on a front side and a rear region on a rear side that are obtained by dividing the pooled water portion into two regions in a front-rear direction, the flush toilet including a configuration where a ratio of an inflow flow rate of flush water into the front region of the pooled water portion in a second half of flushing period in a flushing period to “a total inflow flow rate of flush water into the pooled water portion” is larger than a ratio of an inflow flow rate of flush water into the front region of the pooled water portion in a first half of flushing period to “the total inflow flow rate of flush water into the pooled water portion”.

In the present invention including this configuration, the flow of flush water is formed on the waste receiving surface so that the ratio of the inflow flow rate of flush water into the front region of the pooled water portion in the second half of flushing period in the flushing period in which flush water to flush the waste receiving surface flows into the pooled water portion to “the total inflow flow rate of flush water into the pooled water portion” is larger than the ratio of the inflow flow rate of flush water into the front region of the pooled water portion in the first half of flushing period to “the total inflow flow rate of flush water into the pooled water portion”. Consequently, according to the present invention, the ratio of the inflow flow rate of flush water into the front region of the pooled water portion in the second half of flushing period to “the total inflow flow rate of flush water into the pooled water portion” is increased, so that discharge capacity of fine waste particles in the second half of flushing period can be improved, and the fine waste particles can be inhibited from remaining in the pooled water portion in the second half of flushing period. Therefore, present invention can improve the discharge capacity of waste in the second half of flushing period.

In the present invention, preferably, the pooled water portion is divided into four regions by a front-rear center line that divides the pooled water portion into two regions of the front region and the rear region in the front-rear direction, and a left-right center line that divides the pooled water portion into two regions of a right region and a left region in a left-right direction, and in the first half of flushing period, a main flow of flush water that is formed on the waste receiving surface flows into the front region and/or the rear region of either region of the right region and the left region that is located downstream in a circulating direction of flush water.

In the present invention including this configuration, in the first half of flushing period, the main flow of flush water that is formed on the waste receiving surface flows into the front region and/or the rear region of either region of the right region and the left region that is located downstream in the circulating direction of flush water. Consequently, according to the present invention, in the second half of flushing period, when the circulation of flush water weakens and an inflow region of the main flow of flush water into the pooled water portion changes to shift to an upstream side in the circulating direction, the main flow of flush water easily flows into the front region of the pooled water portion.

In the present invention, preferably, the waste receiving surface of the bowl includes a concave portion formed in a fan shape that spreads from a front portion of the waste receiving surface toward the rear side in a planar view.

In the present invention including this configuration, the waste receiving surface of the bowl includes the concave portion formed in the fan shape that spreads from the front portion of the waste receiving surface toward the rear side in the planar view. Consequently, according to the present invention, when momentum of the circulating flow of flush water in the first half of flushing period or the like is strong and the circulating flow flows on a front side of the concave portion of the waste receiving surface, the flush water can be inhibited from being collected by the concave portion, and when the momentum of the circulating flow of flush water in the second half of flushing period or the like weakens and the circulating flow flows on the rear side of the concave portion of the waste receiving surface, the flush water can be easily collected by the concave portion. It becomes easy to form a push-in flow of waste flowing down from the concave portion on the front side of the waste receiving surface toward the pooled water portion.

In the present invention, preferably, the pooled water portion is divided into four regions by a front-rear center line that divides the pooled water portion into two regions of the front region and the rear region in the front-rear direction, and a left-right center line that divides the pooled water portion into two regions of a right region and a left region in a left-right direction, and a ratio of an inflow flow rate of flush water into the front region in either region of the right region and the left region in the second half of flushing period to “the total inflow flow rate of flush water into the pooled water portion” is larger than a ratio of an inflow flow rate of flush water into each of three other regions to “the total inflow flow rate of flush water into the pooled water portion”.

In the present invention including this configuration, the ratio of the inflow flow rate of flush water into the front region in either region of the right region and the left region in the second half of flushing period to “the total inflow flow rate of flush water into the pooled water portion” is larger than the ratio of each of the inflow flow rates of flush water into the three other regions to “the total inflow flow rate of flush water into the pooled water portion”. Consequently, according to the present invention, in the second half of flushing period, the flow of flush water to the pooled water portion can be strongly formed in the front region of either region of the right region and the left region of the four regions. The discharge capacity of fine waste particles in the second half of flushing period can be further improved, and the discharge capacity of waste in the second half of flushing period can be further improved.

In the present invention, preferably, the bowl includes a well portion that forms the pooled water portion, the flush toilet further includes a discharge trap conduit connected to a bottom of the well portion, the waste receiving surface includes a concave portion formed in a region from a front portion of the waste receiving surface to a side portion of the well portion, the well portion includes a side wall that rises vertically and a front wall that rises vertically, the side wall includes an inclined portion inclined so that a height of a top edge decreases toward front, and the inclined portion extends forward from the vicinity of a rear end of the concave portion.

In the present invention including this configuration, since the well portion includes the inclined portion inclined so that the height of the top edge of the side wall decreases toward the front, a flow from the rear side of the bowl toward the front side forms a forward flow toward the front wall of the well portion while lowering to inside the well portion due to the inclined portion inside the concave portion, and the lowered forward flow hits the front wall to form a vertical circulating flow that rises along the front wall. Further, the waste receiving surface includes a concave portion from a front portion of the waste receiving surface to the side portion of the well portion, and the flow from the rear side of the bowl toward the front side is guided forward from outside the inclined portion. The flush water guided along the concave portion to the front side forms a rearward flow from the concave portion of the front portion of the waste receiving surface toward the well portion. At this time, since the inclined portion extends forward from the vicinity and inside of the rear end of the concave portion, the flow of flush water flowing into the concave portion flows along the concave portion. Consequently, according to the present invention, flush water flows down from the side portion of the well portion to inside the well portion and can be inhibited from colliding with the forward flow in the inclined portion and the rearward flow from the concave portion of the front portion of the waste receiving surface toward the well portion and from disturbing these flows. Therefore, according to the present invention, the vertical circulating flow rising along the front wall and the rearward flow from the concave portion toward the well portion are easily formed without interfering with each other, and the vertical circulating flow rising along the front wall and the rearward flow from the concave portion toward the well portion join each other, can more strongly form the push-in flow from the front of the well portion toward the bottom and can improve waste discharge performance.

In the present invention, preferably, a lowermost portion of the concave portion of the waste receiving surface is disposed below an uppermost portion of the inclined portion of the well portion.

In the present invention including this configuration, the lowermost portion of the concave portion of the waste receiving surface is disposed below the uppermost portion of the inclined portion of the well portion. Consequently, according to the present invention, the forward flow toward the front wall of the well portion while lowering to inside the well portion due to the inclined portion and the rearward flow flowing rearward from the concave portion toward the well portion tend to have different heights, and the forward flow from the inclined portion and the rearward flow from the concave portion can be inhibited from colliding with each other, can join each other and can easily and further strongly form the push-in flow from the front of the well portion toward the bottom.

In the present invention, preferably, the well portion further includes an inducing portion in which a height of a top edge of the side wall is constant behind a rear end of the concave portion.

In the present invention including this configuration, the well portion further includes the inducing portion in which the height of the top edge of the side wall is constant behind the rear end of the concave portion. Consequently, according to the present invention, a flow from the rear side of the bowl toward the front side can be induced as a flow changed forward by the inducing portion behind the rear end of the concave portion, and the forward flow from the inclined portion can be prevented from being easily disturbed. The forward flow from the inclined portion and a rearward flow from the concave portion join each other and can further strongly form the push-in flow from the front of the well portion toward the bottom.

In the present invention, preferably, an uppermost portion of the inclined portion of the top edge of the well portion is formed in front of a rear wall on the rear side of the well portion.

In the present invention including this configuration, the uppermost portion of the inclined portion of the top edge of the well portion is formed in front of the rear wall on the rear side of the well portion. Consequently, according to the present invention, the flow of flush water that is likely to be directed forward on the lateral side of the well portion in front of the rear wall can be divided into a flow lowering along the inclined portion from the uppermost portion of the inclined portion of the top edge of the well portion and a flow guided forward from outside the inclined portion of the top edge of the well portion. When the flow is divided on the lateral side of the well portion, the flow can be prevented from being easily disturbed. Consequently, the forward flow toward the front wall of the well portion while lowering to inside the well portion due to the inclined portion and the rearward flow flowing rearward from the concave portion toward the well portion can be prevented from being easily disturbed. According to the present invention, when the vertical circulating flow rising along the front wall and the rearward flow from the concave portion toward the well portion join each other, the flows can be inhibited from colliding with each other and can further strongly form the push-in flow from the front of the well portion toward the bottom.

In the present invention, preferably, a maximum value of a lateral width of the concave portion is smaller than a maximum value of a lateral width of the well portion in a planar view.

In the present invention including this configuration, the maximum value of the lateral width of the concave portion is smaller than the maximum value of the lateral width of the well portion in the planar view. Therefore, according to the present invention, the forward flow on the lateral side of the well portion tends to form a forward flow toward the front wall of the well portion while lowering to inside the well portion due to the inclined portion, and flush water tends to flow forward as it is. Therefore, the rearward flow flowing rearward from the concave portion toward the well portion can be inhibited from growing excessively and colliding with the forward flow from the inclined portion, and these flows join each other and can further strongly form the push-in flow from the front of the well portion toward the bottom.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view showing a flush toilet according to one embodiment of the present invention;

FIG. 2 is a cross-sectional view taken along the II-II line of FIG. 1 ;

FIG. 3 is a cross-sectional view taken along the III-III line of FIG. 1 ;

FIG. 4 is a cross-sectional view taken along the IV-IV line of FIG. 2 ;

FIG. 5 is a cross-sectional view taken along the V-V line of FIG. 3 ;

FIG. 6 is a cross-sectional view taken along the VI-VI line of FIG. 3 ;

FIG. 7 is a cross-sectional view taken along the VII-VII line of FIG. 3 ;

FIG. 8 is a cross-sectional view taken along the VIII-VIII line of FIG. 3 ;

FIG. 9 is a cross-sectional view taken along the IX-IX line of FIG. 3 ;

FIG. 10 is a cross-sectional view taken along the X-X line of FIG. 3 ;

FIG. 11 is a cross-sectional view taken along the XI-XI line of FIG. 3 ;

FIG. 12 is a cross-sectional view taken along the XII-XII line of FIG. 3 ;

FIG. 13 is a cross-sectional view taken along the XIII-XIII line of FIG. 3 ;

FIG. 14 is a view explaining flow of flush water in a pooled water portion of a well portion and in a first half of flushing period in the cross-sectional view of FIG. 4 ;

FIG. 15 is a diagram showing the result of simulation of kinetic energy of flush water flowing into each region in a flushing period in the flush toilet according to one embodiment of the present invention;

FIG. 16 is a diagram showing the result of simulation of the remaining number of fine waste particles to discharge in the flushing period in the flush toilet according to one embodiment of the present invention; and

FIG. 17 is a view explaining flow of flush water in a second half of flushing period in the cross-sectional view of FIG. 4 .

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Next, with reference to FIGS. 1 to 4 , a flush toilet according to one embodiment of the present invention will be described.

As shown in FIGS. 1 to 3 , the flush toilet 1 is a flush toilet that is flushed with flush water supplied from a flush water supply source to discharge waste. The flush toilet 1 is a wash-out type toilet that pushes away waste by flow of water due to drop of water in a bowl. The flush toilet 1 includes a toilet main body 2 and a storage tank 4 that stores flush water to flush the toilet main body 2. The toilet main body 2 is made of pottery. The toilet main body 2 includes a bowl 6 that receives waste on a front side. Further, a common water passage 8 having an upstream end communicating with the storage tank 4 is formed in an upper rear part of the bowl 6, and further, a discharge conduit 10 for discharging waste is formed in a lower rear part of the bowl 6. The flush toilet 1 may be a so-called siphon-type flush toilet that sucks waste in the bowl 6 by use of a siphon action to discharge the waste to outside at once from a discharge trap conduit. Hereinafter, in the description of one embodiment of the present invention, a proximal side seen from a user using the flush toilet 1 (side of a user standing in front of the flush toilet 1 to use the flush toilet 1) is described as a front side, a distal side seen from the user is described as a rear side, a right side seen from front of the flush toilet 1 is described as a right side, and a left side seen from the front is described as a left side.

A discharge trap conduit 12 is connected to below the bowl 6. The discharge trap conduit 12 includes an inlet conduit 12 a connected to a bottom of a well portion described later in the bowl 6, an ascending conduit 12 b extending diagonally upward and rearward from the inlet conduit 12 a, and a descending conduit 12 c descending from the ascending conduit 12 b. The bowl 6 and the discharge trap conduit 12 are made of pottery and are molded integrally with the toilet main body 2. The bowl 6 forms an oval shape with a vertical width of 32 cm to 40 cm in a front-rear direction in a top view and a lateral width of 22 cm to 30 cm.

The storage tank 4 corresponds to a flush water supply source, and a discharge valve 14 is provided in the storage tank 4 and is opened and closed with an operation lever (not shown). The flush toilet 1 may be supplied with flush water by a pump or the like without via the storage tank 4.

The bowl 6 includes a bowl-shaped waste receiving surface 16, a rim 18 formed above the waste receiving surface 16, and a well portion 20 formed below the waste receiving surface 16 to form a pooled water portion 28 having a pooled water surface WO (21). Here, an inner peripheral surface 18 a of the rim 18 has a shape that is overhung inward as shown in FIG. 12 and the like described later, and hence flush water circulating as described later does not rush outward. The well portion 20 forms a substantially triangular shape closer to an oval shape (elliptic shape with a tapered front side) than the substantially triangular pooled water surface WO and is formed in a size with a vertical width of 200 mm to 240 mm in the front-rear direction in a top view and a lateral width of 150 mm to 190 mm in a left-right direction. Here, a pooled water surface 21 of the well portion 20 is substantially triangular, has a vertical width of 160 mm to 180 mm in the top view and a lateral width of 125 mm to 145 mm, and is formed larger (enlarged) than a pooled water surface of a conventional wash-out type flush toilet.

A first spouting port 22, which is a spouting port to spout flush water, is formed in front of a central portion of the bowl 6 divided into two equal parts in the front-rear direction on the left side seen from front of the inner peripheral surface of the rim 18, and a second spouting port 24 is further formed in the rim 18 behind the central portion on the right side seen from the front. The first spouting port 22 and the second spouting port 24 form a circulating flow that circulates in the same direction (counterclockwise direction). The common water passage 8 formed in the upper rear part of the flush toilet 1 as described above extends to the front of the bowl and then branches to the left and right to supply flush water to the first spouting port 22 or the second spouting port 24. Alternatively, there may be one or three or more spouting ports to spout flush water. Further, by directing, in an opposite direction, a spouting orientation of the spouting port such as the first spouting port 22 or the second spouting port 24, a circulating flow in a clockwise circulating direction may be formed in the bowl.

Next, the waste receiving surface 16 will be described with reference to FIGS. 1 to 13 .

The waste receiving surface 16 includes a concave portion 26 formed in a region from a front portion of the waste receiving surface 16 to a side portion of the well portion 20. As shown in FIG. 4 , the concave portion 26 is formed in a fan shape that spreads rearward from the front portion of the waste receiving surface 16 toward the rear side in a planar view. The concave portion 26 forms a further recessed portion so as to be further deeper with respect to a surrounding surface of the concave portion 26 of the waste receiving surface 16 (for example, if a curved surface is formed to fit a surrounding shape, the portion is formed by intentionally flattening a part of the curved surface that originally convexly protrudes, or a flat surface is recessed downward to form the portion). The concave portion 26 forms a flush water inducing portion lower than the surrounding waste receiving surface from a rear end 26 a to the front portion of the waste receiving surface. Further, the rear end 26 a of the concave portion 26 is smoothly coupled to the surrounding waste receiving surface 16. The rear end 26 a is located in front of a portion of a side wall 30 in which a width in the left-right direction between left and right side walls 30 of the well portion 20 is maximized. Further, the rear end 26 a is located behind a front wall 32 of the well portion 20 in a top view and is located in a middle region A2 (see FIG. 2 ) described later.

As for the concave portion 26, an inflected portion of the curved surface is difficult to represent on the drawing, and hence a region of the concave portion 26 is virtually shown as a region inside an alternate long and short dash line in FIG. 4 . In such a cross section as shown in FIG. 5 , the concave portion 26 is formed in a region B1 on the waste receiving surface 16. Outer ends 26 b of the concave portion 26 (opposite ends of the region B1) form inflection points where the surface changes downward with respect to the surrounding waste receiving surface 16. A bottom 26 c of the concave portion 26 in the region B1 is shallowly formed.

In such a cross section as shown in FIG. 6 , the concave portion 26 is formed in a region B2 on the waste receiving surface 16. Outer ends 26 b of the concave portion 26 (opposite ends of the region B2) form inflection points where the surface changes downward with respect to the surrounding waste receiving surface 16. A width between the outer ends 26 b in the region B2 is larger than the width between the outer ends 26 b in the region B1. The bottom 26 c of the concave portion 26 in the region B2 is deeply formed. A height (depth) between the outer end 26 b and the bottom 26 c in the region B2 is larger (deeper) than a height (depth) between the outer end 26 b and the bottom 26 c in the region B1. A curvature radius of the bottom 26 c shown in FIG. 6 is larger than a curvature radius of the bottom 26 c shown in FIG. 5 .

In such a cross section as shown in FIG. 7 , the concave portion 26 is formed in a region B3 on the waste receiving surface 16. Outer ends 26 b of the concave portion 26 (opposite ends of the region B3) form inflection points where the surface changes downward with respect to the surrounding waste receiving surface 16. A width between the outer ends 26 b in the region B3 is larger than the width between the outer ends 26 b in the region B2. A height (depth) between the outer end 26 b and the bottom 26 c in the region B3 is larger (deeper) than the height (depth) between the outer end 26 b and the bottom 26 c in the region B2. A curvature radius of the bottom 26 c shown in FIG. 7 is larger than the curvature radius of the bottom 26 c shown in FIG. 6 .

In such a cross section as shown in FIG. 8 , the concave portion 26 is formed in a region B4 on the waste receiving surface 16. Outer ends 26 b of the concave portion 26 (opposite ends of the region B4) form inflection points where the surface changes downward with respect to the surrounding waste receiving surface 16. A width between the outer ends 26 b in the region B4 is larger than the width between the outer ends 26 b in the region B3. A height (depth) between the outer end 26 b and the bottom 26 c in region B4 is larger (deeper) than the height (depth) between the outer end 26 b and the bottom 26 c in the region B3. A curvature radius of the bottom 26 c shown in FIG. 8 is larger than the curvature radius of the bottom 26 c shown in FIG. 7 .

In such a cross section as shown in FIG. 9 , the concave portion 26 is formed in a region B5 on the waste receiving surface 16. Outer ends 26 b of the concave portion 26 (opposite ends of the region B5) form inflection points where the surface changes downward with respect to the surrounding waste receiving surface 16. A width between the outer ends 26 b in the region B5 is larger than the width between the outer ends 26 b in the region B4. A height (depth) between the outer end 26 b and the bottom 26 c in the region B5 is larger (deeper) than the height (depth) between the outer end 26 b and the bottom 26 c in the region B4. At such a position of the cross section as shown in FIG. 9 , the bottom 26 c becomes a lowermost portion 26 e at the lowest position of the concave portion 26. The lowermost portion 26 e of the concave portion 26 is disposed below an uppermost portion 38 a of an inclined portion 38 of the well portion 20 described later. A curvature radius of the bottom 26 c shown in FIG. 9 is larger than the curvature radius of the bottom 26 c shown in FIG. 8 .

In such a cross section as shown in FIG. 10 , the concave portion 26 is formed in a region B6 on the waste receiving surface 16. At a position of this cross section, the inclined portion 38 of a top edge 36 of the side wall 30 is formed inside the concave portion 26. The concave portion 26 is recessed by flattening a part of a curved surface that protrudes convexly (curved surface connecting the waste receiving surface 16 and the inclined portion 38). Outer ends 26 b (opposite ends of the region B6) outside the concave portion 26 form inflection points where the surface changes downward with respect to the surrounding waste receiving surface 16. An inner end 26 d inside the concave portion 26 (end inside the region B6) forms an inflection point where the surface further changes downward from the concave portion 26 toward the inclined portion 38. A lateral width between the left and right outer ends 26 b outside the concave portion 26 is larger than a lateral width between the left and right outer ends 26 b in the region B5 shown in FIG. 9 .

In such a cross section as shown in FIG. 11 , the concave portion 26 is formed in a region B7 on the waste receiving surface 16. The inclined portion 38 is formed inside the concave portion 26. The concave portion 26 is recessed so as to flatten a part of a curved surface that protrudes convexly.

Outer ends 26 b outside the concave portions 26 (opposite ends of the region B7) form inflection points where the surface changes downward with respect to the surrounding waste receiving surface 16. The inner end 26 d inside the concave portion 26 (inner end inside the region B7) forms an inflection point where the surface further changes downward from the concave portion 26 toward the inclined portion 38. A width between the outer end 26 b and the inner end 26 d in each of the regions B7 is smaller than the width between the outer end 26 b and the inner end 26 d in each of the regions B6. A lateral width between the left and right outer ends 26 b outside the concave portions 26 is larger than the lateral width from the outer end 26 b of the right region B6 to the outer end 26 b of the left region B6 shown in FIG. 10 .

In such a cross section as shown in FIG. 12 , the concave portion 26 is formed in a region B8 on the waste receiving surface 16. The inclined portion 38 is formed inside the concave portion 26. The concave portion 26 is recessed so as to flatten a part of the curved surface that protrudes convexly. Outer ends 26 b outside concave portions 26 (opposite ends of the region B8) form inflection points where the surface changes downward with respect to the surrounding waste receiving surface 16. The inner ends 26 d inside the concave portions 26 (ends inside the regions B8) form inflection points where the surface further changes downward from the concave portion 26 toward the inclined portion 38. A width between the outer end 26 b and the inner end 26 d in each of the regions B8 is smaller than the width between the outer end 26 b and the inner end 26 d in each of the regions B7. A lateral width between the left and right outer ends 26 b outside the concave portions 26 is larger than the lateral width from the outer end 26 b of the right region B7 to the outer end 26 b of the left region B7 shown in FIG. 11 . The lateral width between the outer ends 26 b on opposite sides of the region B8 is defined as a maximum value W1 of the lateral width of the concave portion 26. As shown in FIG. 4 , the maximum value W1 of the lateral width of the concave portion 26 is smaller than a maximum value W2 of the lateral width of the well portion 20 in a planar view. In a portion forming a maximum width W2 of the lateral width of the well portion 20, an inducing portion 40 is formed at the top edge 36, and the concave portion 26 is not formed. Therefore, a circulating flow that circulates from the rear side to the front side is easily guided from the inducing portion 40 to an inclined portion 38 side in the portion forming the maximum value of the lateral width of the well portion 20.

In such a cross section as shown in FIG. 13 , the concave portion 26 is not formed, and the inducing portion 40 at the top edge 36 is formed on the waste receiving surface 16.

Next, a structure of the well portion 20 will be described in detail with reference to FIGS. 1 to 4 .

In the well portion 20, the pooled water portion 28 is formed in which the pooled water surface WO is shown with an alternate long and short dash line. The well portion 20 includes the side wall 30 that rises vertically on the side, the front wall 32 that rises vertically on the front side, a rear wall 34 that rises vertically on the rear side, the inclined portion 38 that inclines the top edge 36 of the side wall 30 to decrease a height of the top edge 36 of the side wall 30 toward the front, and the inducing portion 40 in which the height of the top edge 36 of the side wall 30 is constant behind the rear end 26 a of the concave portion 26.

The front wall 32 is formed to rise from a bottom 33 of the well portion 20. An angle of a front bottom corner portion 41 between the front wall 32 and the bottom 33 is smaller than an angle of a rear bottom corner portion 42 between the rear wall 34 and the bottom 33. Consequently, flush water flowing down from the inclined portion 38 once flows from the pooled water surface into water, and then vertical circulation can be more easily formed along the front wall 32. Further, a vertically circulating flow at this time is a flow that rises from the bottom 33 to the front wall 32 along the front bottom corner portion 41 and forms a compact vertical circulating flow to an upper part of the front wall 32. Further, when the angle of the front bottom corner portion 41 is small and the forward flow hits the front bottom corner portion 41 from the bottom, it is easy to form a vertical circulation that rises along the front wall 32. Even if the forward flow does not hit the bottom, the vertical circulating flow can be formed, but when the flow hits the bottom and then rises along the front bottom corner portion 41, the vertical circulating flow can be formed more efficiently.

As shown in FIG. 2 , the inclined portion 38 extends forward from the vicinity and inside of the rear end 26 a of the concave portion 26. As for the inclined portion 38, an inflected portion of a curved surface is difficult to represent on the drawing, and hence in FIGS. 2 to 4 , a region of the inclined portion 38 is virtually shown as a region inside a dashed line. The inclined portion 38 extends forward from a lateral region of the middle region A2 obtained by dividing, in the front-rear direction, the well portion 20 into three regions (front region A1, middle region A2, and rear region A3). The rear end 26 a of the concave portion 26 is also located in the lateral region of the middle region A2. Further, as shown in FIGS. 11 and 12 or the like, the inclined portion 38 forms a curved corner portion in a vertical cross section and forms a shelf-shaped flow channel in an upper part of the inclined portion. The uppermost portion 38 a of the inclined portion 38 is formed in front of the rear wall 34 on the rear side of the well portion 20. The uppermost portion 38 a of the inclined portion 38 is formed as the inflection point that bends downward from the inducing portion 40 and is likely to form a trigger for flush water to start flowing downward and inward. The inclined portion 38 forms a downward slope angle in a range of 2 to 35 degrees with respect to the inducing portion 40. The inclined portion 38 forms a surface inclined to below the inducing portion 40. A lower end of the inclined portion 38 is connected to slightly below a top of the front wall 32. The flush water flowing into the inclined portion 38 is once inhibited from flowing toward the concave portion 26 outside and is difficult to interfere with the flush water flowing over the concave portion 26. Therefore, the flush water flowing from the inclined portion 38 to inside the well portion 20 and the flush water flowing over the concave portion 26 to the front side of the waste receiving surface 16 can be prevented from easily interfering with each other, and two flows can be formed more efficiently and strongly.

The inducing portion 40 extends substantially horizontally rearward from the rear end of the inclined portion 38 toward the rear wall 34. Also, as for the inducing portion 40, an inflected portion of a curved surface is difficult to represent on the drawing, and hence in FIGS. 2 and 3 , a region of the inducing portion 40 is virtually shown as a region inside the dashed line.

Next, with reference to FIGS. 2 and 4 , the flow of flush water in the flush toilet according to one embodiment of the present invention will be described.

First, when the user operates the operation lever (not shown) of the storage tank 4, the discharge valve 14 opens, and flush water is supplied from the storage tank 4 to the common water passage 8. The flush water is spouted from the first spouting port 22 and the second spouting port 24, and as shown by arrows F0, a circulating flow that circulates around the well portion 20 on the waste receiving surface 16 is formed. At this time, in a lateral region of the well portion 20, orientation of flow of flush water is easier to align forward than in front and rear regions of the well portion.

At this time, as shown by an arrow F1, a flow from the rear side toward the front side of the bowl in a lateral inner region of the well portion 20 first flows as a substantially horizontally linear flow, along the inducing portion 40 toward the front side, and is then likely to form a flow lowering toward inside the well portion 20 due to the inclined portion 38. As shown by an arrow F2 (see FIG. 2 ), a main flow of a forward flow toward the front wall 32 of the well portion 20 flows from the pooled water surface 21 into water and hits the front wall 32 from the bottom 33 of the well portion 20 to form a vertical circulating flow that rises along the front wall 32.

Further, as shown by an arrow F3, the flow from the rear side of the bowl toward the front side in an outer region on the side of the well portion 20 is easily guided forward from outside the inclined portion 38 to form a flow guided forward along the concave portion 26. At this time, the flow of flush water flowing into the concave portion 26 is once guided forward along the concave portion 26 to flow down into the inclined portion 38 side and the well portion 20 and can be inhibited from colliding with the forward flow in the inclined portion 38 and rearward flow from the concave portion 26 toward the well portion 20 and from disturbing these flows as described later.

As shown by an arrow F4, part of flush water guided forward along the concave portion 26 forms a rearward flow from the concave portion 26 of the front portion of the waste receiving surface 16 toward the well portion 20. The concave portion 26 forms a portion that is more recessed than the waste receiving surface 16 and is therefore likely to form a rearward flow from the concave portion 26 toward the well portion 20.

As shown by an arrow F5, the vertical circulating flow (flow of the arrow F2) rising along the front wall 32 and the rearward flow (flow of the arrow F4) from the concave portion 26 toward the well portion 20 join each other and can more strongly form a push-in flow from the front of the well portion 20 toward a bottom. Therefore, the joined flow can strengthen the push-in flow from the front of the well portion 20 toward the bottom, and further improve waste discharge performance. Alternatively, the vertical circulating flow rising along the front wall may be formed by hitting the front wall 32 of the well portion 20, instead of the bottom 33 of the well portion 20. Further, this push-in flow can improve discharge capacity of fine waste particles or maintain high discharge capacity of fine waste particles. The waste pushed into water with the flush water is discharged downstream from the discharge trap conduit 12. Although such a push-in flow as shown by the arrow F5 is easily formed throughout a flushing period, as will be described later, in a second half of flushing period E3 (see FIG. 15 ), a ratio of an inflow flow rate of flush water into a front region (third region D3 and fourth region D4) of the well portion 20 and the pooled water surface 21 of the pooled water portion 28 shown in FIG. 14 to “a total inflow flow rate of flush water into the pooled water portion” is likely to be increased. Therefore, the push-in flow shown by the arrow F5 as described above is more likely to be formed.

Furthermore, when momentum of the circulating flow of flush water in an orbital direction is strong and the circulating flow flows on the front side of the concave portion 26 of the waste receiving surface 16 (first half of flushing period E1 shown in FIG. 15 ), the depth of the concave portion 26 at a passing position is shallow, and hence flush water can be inhibited from being collected by the concave portion 26. When the momentum of the circulating flow of flush water weakens and the circulating flow flows on the rear side of the concave portion 26 of the waste receiving surface 16 (second half of flushing period E3 shown in FIG. 15 ), the concave portion 26 at a deep passing position makes it easier to collect the flush water by the concave portion 26. This can further facilitate the formation of the push-in flow of waste flowing down from the concave portion 26 on the front side of the waste receiving surface 16 toward the pooled water portion.

Next, the pooled water portion will be described in detail with reference to FIG. 14 .

The well portion 20 forms the pooled water surface 21 as the pooled water portion (pooled water surface WO shown with an alternate long and short dash line in FIG. 3 ). The pooled water surface 21 is divided into four regions by a front-rear center line C1 that divides the pooled water surface 21 into two regions of a front region and a rear region in the front-rear direction, and a left-right center line C2 that divides the pooled water surface into two regions of a right region and a left region in a left-right direction. The pooled water surface 21 has a front region on a front side and a rear region on a rear side of the pooled water surface 21 divided into the two regions in the front-rear direction. In the front region of the pooled water surface 21, a depth from the pooled water surface to the bottom is smaller than in the rear region, and a function of pushing in floating waste with the flow from above by use of the vertical circulating flow effectively and easily works. The front-rear center line C1 is a line extending in the left-right direction at an intermediate position between the front wall 32 and the rear wall 34 in the pooled water surface 21. The left-right center line C2 is a line extending in the front-rear direction at an intermediate position between the right side wall 30 and the left side wall 30 in the pooled water surface 21. In the pooled water surface 21, the four regions divided by the front-rear center line C1 and the left-right center line C2 are a first region D1, a second region D2, the third region D3, and the fourth region D4. In the present embodiment, the pooled water portion is defined by the pooled water surface, and the pooled water portion may be defined by the well portion 20. In this case, the well portion 20 can be defined to be divided into four regions by the front-rear center line C1 that divides the well portion 20 into two regions of a front region and a rear region in the front-rear direction and the left-right center line C2 that divides the well portion into two regions of a right region and a left region in the left-right direction.

Next, with reference to FIGS. 14 to 16 , the flow of flush water in the flush toilet according to one embodiment of the present invention will be described.

FIG. 15 shows the result of simulation of kinetic energy of flush water flowing into the respective regions (first region D1, second region D2, third region D3 and fourth region D4) of the pooled water surface 21 of the pooled water portion 28, that is, inflow flow rates in a flushing period in the flush toilet of the present embodiment. In FIG. 15 , a vertical axis indicates change in kinetic energy [J] of flush water, and a horizontal axis indicates elapse of time. On the horizontal axis, start of operation of the operation lever is set to start at time 0 [S]. The flushing period in which flush water to flush the waste receiving surface flows into the pooled water portion 28 is a period from time T0 [S] to time T1 [S]. At time T0, inflow of flush water into the pooled water surface 21 starts, and at time T1, inflow of flush water into the pooled water surface 21 of the pooled water portion 28 that contributes to flushing is substantially ended. When the inflow flow rate of flush water into the pooled water surface 21 decreases to such an extent that the inflow flow rate does not substantially contribute to the flushing, the inflow of flush water contributing to the flushing into the pooled water surface 21 is ended (time T1). The flushing period is divided into three equal parts to define a first half of flushing period E1, a middle of flushing period E2, and a second half of flushing period E3. The start time of inflow of flush water into the pooled water surface 21 is about the same timing as time to start spouting from the spouting port, and hence the flushing period may be a period to spout flush water and may be set to a period from the time TO [S] to start spouting water from the spouting port to the time T1 [S] when the spouting of water from the spouting port is ended.

After the start of flushing, in the first half of flushing period E1, a ratio of an inflow flow rate of flush water into the rear region (first region D1 and second region D2) of the pooled water portion 28 (pooled water surface 21) shown by arrows F11 to “the total inflow flow rate of flush water into the pooled water portion 28” is larger than a ratio of an inflow flow rate of flush water into the front region (third region D3 and fourth region D4) of the pooled water portion 28 (pooled water surface 21) shown by arrows F12 to “the total inflow flow rate of flush water into the pooled water portion 28”.

In the second half of flushing period E3, a ratio of an inflow flow rate of flush water into the front region (third region D3 and fourth region D4) of the pooled water portion 28 (pooled water surface 21) shown by arrows F13 to “the total inflow flow rate of flush water into the pooled water portion 28” is larger than a ratio of an inflow flow rate of flush water into the rear region (first region D1 and second region D2) of the pooled water portion 28 (pooled water surface 21) shown by arrows F14 to “the total inflow flow rate of flush water into the pooled water portion 28”.

Further, the ratio of the inflow flow rate of flush water into the front region (third region D3 and fourth region D4) of the pooled water portion 28 (pooled water surface 21) shown by the arrows F13 in the second half of flushing period E3 to the “the total inflow flow rate of flush water into the pooled water portion 28” is larger than the ratio of the inflow flow rate of flush water into the front region (third region D3 and fourth region D4) of the pooled water portion 28 (pooled water surface 21) shown by the arrows F12 in the first half of flushing period E1 to “the total inflow flow rate of flush water into the pooled water portion 28”. Thus, the ratio of the inflow flow rate into the front region of the pooled water portion 28 (pooled water surface 21) in the second half of flushing period E3 to “the total inflow flow rate of flush water into the pooled water portion 28” is increased, so that the discharge capacity of fine waste particles in the second half of flushing period E3 can be improved, or the discharge capacity of fine waste particles can be maintained high also in the second half of flushing period E3.

In the first half of flushing period E1, the ratio of the inflow flow rate of flush water into the front region (third region D3 and fourth region D4) of the pooled water portion 28 (pooled water surface 21) to “the total inflow flow rate of flush water into the pooled water portion 28” decreases. Then, the ratio of the inflow flow rate of flush water into the front region (third region D3 and fourth region D4) of the pooled water portion 28 (pooled water surface 21) in the second half of flushing period E3 to “the total inflow flow rate of flush water into the pooled water portion 28” increases. Then, it can be confirmed that the ratio of the inflow flow rate of flush water into the front region (third region D3 and fourth region D4) of the pooled water surface 21 in the inflow flow rate of flush water into the pooled water surface 21 in the second half of flushing period is larger than the ratio of the inflow flow rate of flush water into the front region (third region D3 and fourth region D4) of the pooled water portion 28 (pooled water surface 21) in the first half of flushing period E1 to “the total inflow flow rate of flush water into the pooled water portion 28”.

FIG. 16 shows the result of simulation of the remaining number of fine waste particles to discharge in the flushing period in the flush toilet of the present embodiment. In FIG. 16 , a vertical axis indicates the remaining number of fine waste particles to discharge, and a horizontal axis indicates time [S]. In this simulation, the fine waste particles are defined as fine particles, and immediately after the start of flushing, the remaining number of fine waste particles is set to 2500 [particles]. The flushing period in which flush water is spouted is a period from time T0 [S] to time T1 [S], and in the same manner as in FIG. 15 , the flushing period is divided into three equal periods, to define the first half of flushing period E 1, the middle of flushing period E2 and the second half of flushing period E3.

It is seen that the above-described increase in ratio of the inflow flow rate into the front region of the pooled water portion 28 (pooled water surface 21) in the second half of flushing period E3 to “the total inflow flow rate of flush water into the pooled water portion 28” can improve the discharge capacity of the fine waste particles in the second half of flushing period E3 or can maintain the discharge capacity of the fine waste particles to be high also in the second half of flushing period E3, and can discharge the fine waste particles until the waste is reduced and substantially eliminated in the second half of flushing period. In addition, not only the discharge capacity of the fine waste particles but also the discharge capacity of waste in the second half of flushing period can be improved.

Further, in the flush toilet of the present embodiment, as shown by arrows F15, the main flow of flush water that is formed on the waste receiving surface 16 in the first half of flushing period E1 (or middle of flushing period E2) flows into the front region (third region D3) and/or the rear region (second region D2) in either region (right region or left region) of the right region (second region D2 and third region D3) and the left region (first region D1 and fourth region D4) that is located downstream in the circulating direction of flush water as seen from the front portion of the waste receiving surface 16, for example, in the right region (second region D2 and third region D3) in the present embodiment.

Consequently, as shown in FIG. 17 , in the second half of flushing period E3, when the circulation of flush water weakens and an inflow region of main flow of flush water into the pooled water portion 28 (pooled water surface 21) changes to shift to an upstream side in the circulating direction (circulating direction shown by arrows F10), as shown by arrows F16, the main flow of flush water can easily flow into the front region (third region D3 and fourth region D4) of the pooled water portion 28 (pooled water surface 21). Therefore, it can be seen that the discharge capacity of fine waste particles in the second half of flushing period E3 is improved, or the discharge capacity of fine waste particles is maintained high also in the second half of flushing period E3 and that the remaining fine waste particles can be reduced and discharged in the second half of flushing period. In addition, not only the discharge capacity of fine waste particles but also the discharge capacity of waste in the second half of flushing period can be improved.

As for the inflow flow rate of flush water into the pooled water portion 28 (pooled water surface 21) in the second half of flushing period E3, a ratio of the inflow flow rate into the front region (fourth region D4 or third region D3) in either region (right region or left region) of the right region (second region D2 and third region D3) and the left region (first region D1 and fourth region D4) to “the total inflow flow rate of flush water into the pooled water portion 28” is larger than a ratio of each of inflow flow rates into three other regions to “the total inflow flow rate of flush water into the pooled water portion 28”. For example, in FIGS. 15 and 17 , a ratio of the inflow flow rate of flush water into the front region (fourth region D4) in either region (for example, the left region) of the right region (second region D2 and third region

D3) and the left region (first region D1 and fourth region D4) in the second half of flushing period E3 to “the total inflow flow rate of flush water into the pooled water portion 28” (the ratio of the inflow flow rate shown by arrows F17 to the total inflow flow rate) is larger than the ratio of each of the inflow flow rates into three other regions (first region D1, second region D2 and third region D3) to “the total inflow flow rate of flush water into the pooled water portion 28” (the ratio of each of the inflow flow rates shown by arrows F18, F19 and F20 to the total inflow flow rate). For example, the inflow flow rate of flush water is calculated as an averaged value in the second half of flushing period E3. The fine waste particles and waste pushed into water with the flush water are discharged downstream from the discharge trap conduit 12, to end the flushing.

According to the flush toilet 1 of one embodiment of the present invention described above, the flow of flush water is formed on the waste receiving surface 16 so that the ratio of the inflow flow rate of flush water into the front region of the pooled water portion 28 (pooled water surface 21) in the second half of flushing period E3 in the flushing period in which flush water to flush the waste receiving surface 16 flows into the pooled water portion 28 (pooled water surface 21) to “the total inflow flow rate of flush water into the pooled water portion 28” is larger than the ratio of the inflow flow rate of flush water into the front region of the pooled water portion 28 (pooled water surface 21) in the first half of flushing period E1 to “the total inflow flow rate of flush water into the pooled water portion 28”. Consequently, the ratio of the inflow flow rate into the front region of the pooled water portion 28 (pooled water surface 21) in the second half of flushing period E3 is increased, so that discharge capacity of fine waste particles in the second half of flushing period E3 can be improved, and the fine waste particles can be inhibited from remaining on the pooled water surface 21 in the second half of flushing period E3. Therefore, the discharge capacity of waste in the second half of flushing period E3 can be improved.

Further, according to the flush toilet 1 of the present embodiment, the main flow of flush water that is formed on the waste receiving surface 16 in the first half of flushing period E1 flows into the front region and the rear region in either region of the right region and the left region that is located downstream along the circulating direction of flush water on the waste receiving surface 16. Consequently, in the second half of flushing period E3, when the circulation of flush water weakens and the inflow region of the main flow of flush water into the pooled water portion 28 (pooled water surface 21) changes to shift to the upstream side in the circulating direction, the main flow of flush water can easily flow into the front region of the pooled water surface 21.

Furthermore, according to the flush toilet 1 of the present embodiment, the waste receiving surface 16 of the bowl 6 includes the concave portion 26 formed in the fan shape that spreads from the front portion of the waste receiving surface 16 toward the rear side in the planar view. Consequently, when momentum of the circulating flow of flush water is strong and the circulating flow flows on the front side of the concave portion 26 of the waste receiving surface 16, the flush water can be inhibited from being collected by the concave portion 26, and when the momentum of the circulating flow of flush water weakens and the circulating flow flows on the rear side of the concave portion 26 of the waste receiving surface 16, the flush water can be easily collected by the concave portion 26. It becomes easy to form a push-in flow of waste flowing down from the concave portion 26 on the front side of the waste receiving surface 16 toward the pooled water portion 28 (pooled water surface 21).

In addition, according to the flush toilet 1 of the present embodiment, the ratio of the inflow flow rate of flush water into the front region in either region of the right region and the left region of the pooled water portion 28 (pooled water surface 21) in the second half of flushing period E3 to “the total inflow flow rate of flush water into the pooled water portion 28” is larger than the ratio of each of the inflow flow rates of flush water into the three other regions to “the total inflow flow rate of flush water into the pooled water portion 28”. Consequently, in the second half of flushing period E3, the flow of flush water to the pooled water portion 28 (pooled water surface 21) can be strongly formed in the front region of either region of the right region and the left region of the four regions. The discharge capacity of fine waste particles in the second half of flushing period E3 can be further improved, and the discharge capacity of waste in the second half of flushing period E3 can be further improved.

Furthermore, according to the flush toilet 1 of one embodiment of the present invention described above, since the well portion 20 includes the inclined portion 38 inclined so that the height of the top edge 36 of the side wall 30 decreases toward the front, the forward flow from the rear side of the bowl 6 forms a forward flow toward the front wall 32 of the well portion 20 while lowering to inside the well portion 20 due to the inclined portion 38 inside the concave portion 26, and the lowered forward flow hits the front wall 32 to form a vertical circulating flow that rises along the front wall 32. Further, the waste receiving surface 16 includes the concave portion 26 recessed downward from the front portion of the waste receiving surface 16 to the side portion of the well portion 20, and the flow from the rear side of the bowl 6 toward the front side is guided forward from outside the inclined portion 38. The flush water guided along the concave portion 26 to the front side forms a rearward flow from the concave portion 26 of the front portion of the waste receiving surface 16 toward the well portion 20. At this time, since the inclined portion 38 extends forward from the vicinity and inside of the rear end 26 a of the concave portion 26, the flow of flush water into the concave portion 26 flows along the concave portion 26. Consequently, flush water flows down from the side portion of the well portion 20 to inside the well portion 20 and can be inhibited from colliding with the forward flow in the inclined portion 38 and the rearward flow from the concave portion 26 of the front portion of the waste receiving surface 16 toward the well portion 20 and from disturbing these flows. According to this configuration, the vertical circulating flow rising along the front wall 32 and the rearward flow from the concave portion 26 toward the well portion 20 are easily formed without interfering with each other, and the vertical circulating flow rising along the front wall 32 and the rearward flow from the concave portion 26 toward the well portion 20 join each other, can more strongly form the push-in flow from the front of the well portion 20 toward the bottom and can improve waste discharge performance.

Also, according to the flush toilet 1 of the present embodiment, the lowermost portion 26 e of the concave portion 26 of the waste receiving surface 16 is disposed below the uppermost portion 38 a of the inclined portion 38 of the well portion 20. Consequently, the forward flow toward the front wall 32 of the well portion 20 while lowering to inside the well portion 20 due to the inclined portion 38 and the rearward flow flowing rearward from the concave portion 26 toward the well portion 20 tend to have different heights, and the forward flow from the inclined portion 38 and the rearward flow from the concave portion 26 can be inhibited from colliding with each other and can join each other to easily and further strongly form the push-in flow from the front of the well portion 20 toward the bottom.

Further, according to the flush toilet 1 of the present embodiment, the well portion 20 further includes the inducing portion 40 in which the height of the top edge 36 of the side wall 30 is constant behind the rear end 26 a of the concave portion 26. Consequently, the forward flow from the rear side of the bowl 6 can be induced as the flow changed forward by the inducing portion 40 behind the rear end 26 a of the concave portion 26, and the forward flow from the inclined portion 38 can be prevented from being easily disturbed. The forward flow from the inclined portion 38 and the rearward flow from the concave portion 26 join each other and can further strongly form the push-in flow from the front of the well portion 20 toward the bottom.

Additionally, according to the flush toilet 1 of the present embodiment, the uppermost portion 38 a of the inclined portion 38 of the top edge 36 of the well portion 20 is formed in front of the rear wall 34 on the rear side of the well portion 20. Consequently, the flow of flush water that is likely to be directed forward on the lateral side of the well portion 20 in front of the rear wall 34 can be divided into a flow lowering along the inclined portion 38 from the uppermost portion 38 a of the inclined portion 38 of the top edge 36 of the well portion 20 and a flow guided forward from outside the inclined portion 38 of the top edge 36 of the well portion 20. When the flow is divided on the lateral side of the well portion 20, the flow can be prevented from being easily disturbed. Consequently, the forward flow toward the front wall of the well portion 20 while lowering to inside the well portion 20 due to the inclined portion 38 and the rearward flow flowing rearward from the concave portion 26 toward the well portion 20 can be prevented from being easily disturbed. According to the present invention, when the vertical circulating flow rising along the front wall 32 and the rearward flow from the concave portion 26 toward the well portion 20 join each other, the flows can be inhibited from colliding with each other and can further strongly form the push-in flow from the front of the well portion 20 toward the bottom.

Further, according to the flush toilet 1 of the present embodiment, the maximum value W1 of the lateral width of the concave portion 26 is smaller than the maximum value W2 of the lateral width of the well portion 20 in the planar view. Therefore, the forward flow on the lateral side of the well portion tends to form a forward flow toward the front wall 32 of the well portion 20 while lowering to inside the well portion 20 due to the inclined portion 38, and flush water tends to flow forward as it is. Therefore, the rearward flow flowing rearward from the concave portion 26 toward the well portion 20 can be inhibited from growing excessively and colliding with the forward flow from the inclined portion 38, and these flows join each other and can further strongly form the push-in flow from the front of the well portion 20 toward the bottom. 

What is claimed is:
 1. A flush toilet that is flushed with flush water supplied from a flush water supply source to discharge waste, the flush toilet comprising: a bowl that receives waste, the bowl including: a bowl-shaped waste receiving surface, a rim formed above the waste receiving surface, a spouting port that is formed in the rim and that spouts flush water, and a pooled water portion formed below the waste receiving surface, the pooled water portion having a front region on a front side and a rear region on a rear side that are obtained by dividing the pooled water portion into two regions in a front-rear direction, the flush toilet including a configuration where a ratio of an inflow flow rate of flush water into the front region of the pooled water portion in a second half of flushing period in a flushing period to “a total inflow flow rate of flush water into the pooled water portion” is larger than a ratio of an inflow flow rate of flush water into the front region of the pooled water portion in a first half of flushing period to “the total inflow flow rate of flush water into the pooled water portion”.
 2. The flush toilet according to claim 1, wherein the pooled water portion is divided into four regions by a front-rear center line that divides the pooled water portion into two regions of the front region and the rear region in the front-rear direction, and a left-right center line that divides the pooled water portion into two regions of a right region and a left region in a left-right direction, and in the first half of flushing period, a main flow of flush water that is formed on the waste receiving surface flows into the front region and/or the rear region of either region of the right region and the left region that is located downstream in a circulating direction of flush water.
 3. The flush toilet according to claim 1, wherein the waste receiving surface of the bowl comprises a concave portion formed in a fan shape that spreads from a front portion of the waste receiving surface toward the rear side in a planar view.
 4. The flush toilet according to claim 1, wherein the pooled water portion is divided into four regions by a front-rear center line that divides the pooled water portion into two regions of the front region and the rear region in the front-rear direction, and a left-right center line that divides the pooled water portion into two regions of a right region and a left region in a left-right direction, and a ratio of an inflow flow rate of flush water into the front region in either region of the right region and the left region in the second half of flushing period to “the total inflow flow rate of flush water into the pooled water portion” is larger than a ratio of each of inflow flow rates of flush water into three other regions to “the total inflow flow rate of flush water into the pooled water portion”.
 5. The flush toilet according to claim 1, wherein the bowl comprises a well portion that forms the pooled water portion, the flush toilet further comprising a discharge trap conduit connected to a bottom of the well portion, wherein the waste receiving surface comprises a concave portion formed in a region from a front portion of the waste receiving surface to a side portion of the well portion, the well portion comprises a side wall that rises vertically and a front wall that rises vertically, the side wall comprises an inclined portion inclined so that a height of a top edge decreases toward front, and the inclined portion extends forward from the vicinity of a rear end of the concave portion.
 6. The flush toilet according to claim 1, wherein a lowermost portion of the concave portion of the waste receiving surface is disposed below an uppermost portion of the inclined portion of the well portion.
 7. The flush toilet according to claim 1, wherein the well portion further comprises an inducing portion in which a height of a top edge of the side wall is constant behind a rear end of the concave portion.
 8. The flush toilet according to claim 1, wherein an uppermost portion of the inclined portion of the top edge of the well portion is formed in front of a rear wall on the rear side of the well portion.
 9. The flush toilet according to claim 1, wherein a maximum value of a lateral width of the concave portion is smaller than a maximum value of a lateral width of the well portion in a planar view. 